Flame produced by a propane burner for weed control. Photo credit: Denis Giroux
Flaming weeding (also referred to as flaming) is done by attacking weeds using the heat produced by a propane burner with no repercussions on crops or fields. Flaming, although it is largely under-used, has been around for a long time. Flame weeding is particularly useful for vegetable gardens since these crops struggle with weeds and face a constant challenge.
Registered herbicides have variable remanence and may rarely be repeated during the season. More effective on some species, they leave space to those who are less sensitive. Mechanical and manual weeding is essential to limit their development. In order to reduce herbicide use and manual weeding, the use of weed bleaching at different times of the season, combined with mechanical weeding, is an alternative to weed control. It can be done at times when mechanical weeding is difficult, such as in pre-sowing and crop emergence. It is during these two periods that flaming is useful. Weed flaming can also be done during the early post-emergence stages as well as at the later stages of the crop, in July-August. Depending on the sensitivity of the crop, jets can be directed on the row or border of it. These must be covered by baffles that protect the culture from the heat. In all cases, to properly control the different parameters of flaming, producers will have to conduct tests on the farm.
Two types of propane are compatible with flaming. The first is in the form of vapour, the same as found in BBQ tanks. The other, liquid, is the one that is used for forklifts. It is also best suited for more intensive use.
A specific burner will be needed according to the type of propane selected. The amount of propane used will vary according to gas pressure, flow rate, operational speed, use of protective sheets, and stage of weed growth. According to various sources, weed control under optimal conditions requires 100 to 150 kg / ha of propane (1 to 1.5 kg / 100 m2). The operating speed varies from 2 to 7 km / h depending on the capacity of the burners and the stage of the weeds. Flaming controls weeds that have already emerged from the soil, without affecting those that are germinating. Since this method does not reshape the soil, germination of new weeds is reduced.
Denis Giroux, Agr. Réseau de lutte intégrée de Bellechasse et Club agroenvironnemental en horticulture